Implementation and Results of a Feed-Forward Process Controller

The Metropolitan Wastewater Reclamation District (Metro District) commissioned a pilot study in 2011 to test an energy saving process control system at the 80 MGD North Secondary (NSEC) of its Robert W. Hite Treatment Facility. The piloted process control system utilized a feed-forward controller to optimize the dissolved oxygen (DO) set points based on real time influent loading. By linking the DO set points to the loading, the set points dynamically change throughout the day. After using computer software to simulate the predicted savings of utilizing dynamic DO set points, three of twelve trains were converted to utilize the controller and were compared to a baseline set of three trains with constant DO set points. The set of trains utilizing dynamic DO set points required an average of 11% less air. Based on these results, the Metro District has converted the entire NSEC to utilize the process control system.